Lengthwise Shrinkage of Acrylic Acetate Blank Over Time

[Curly]

I have a theory of why it may have shrunk.

When the slabs of acrylic are made they are compressed between two polished platens while the plastic sets perhaps building up some internal stress. The two smooth surfaces of each blank are an indication of that. The vendors cut the slabs on their saws into blanks to sell and we in turn (no pun intended) drill and glue them to tubes and then shape them as we like. Because they are glued to the tubes with epoxy they are initially held from moving. As time goes by the acrylic releases the built in stress by shrinking and the epoxy slowly allowed the movement to occur because of its flexibility.

Now an indicator of the built in stress would show when a vendor is cutting the acrylic slabs up by the long bars being cut off are not straight but have some curve to them. Ed Brown being the only vendor in this thread would be able to confirm if the cut bars are dead straight or occasionally curved. That would also depend on if the slabs are cut into 3/4 square long bars and then into pen blank lengths. Or if they are cut as pen blank length boards and then into width.

Okay now you guys can tell me if I'm possibly right or full of acrylic assitate .

 

[magpens]

Pete,

Thanks for your suggestion ... you may be right. The 5" long blanks were initially straight (I would not have bought them if they were bowed), but that doesn't mean they did not have built in stresses which got released during the post-gluing curing of the acetate.

Or, perhaps, the curing of the acetate creates the stress which leads to the lengthwise contraction which the epoxy, being somewhat flexible, is unable to prevent.

My motive in starting this thread was to make people aware of this phenomenon and to try to find out if anyone else had experienced it. The phenomenon may by peculiar to blanks from a particular maker in Asia and purchased by KMS Tools.

It seems from the replies to my OP that some people, but not many, knew about the phenomenon. Remember, that these pens are "old", having been made 5 years ago. Most people try not to keep their pens around for that long so maybe more pens "do it" than we know about.

Thanks again for your replies .... and thanks to everyone else who responded also.